Method for manufacture of a gas rich in hydrogen



June 15, 1954 J. w. .ul-:WELL

METHOD FOR MANUFACTURE OF A GAS RICH IN HYDROGE Filed Jan. 10. 1948 JSEFH n! .Jn/ELL BYE. mwfw WENEYS Patented `lune 15, `1954 2,681,272 METHOD FOR MANUFACTURE F A GAS RICH IN HY Joseph W. Jewell,

M. W. Kellogg DRGEN Summit, N. J., assignor to Com corporation of Delaware The pany, Jersey City, N. J., a

Application January 10, 1948, Serial No. 1,628

(Cl. lit- 196) 2 Claims.

This invention relates to the method and apparatus for manufacture of a gas rich in hydrogen. In one aspect this invention relates to manufacture of a gaseous mixture of hydrogen and carbon monoxide. 1n another aspect this invention relates to an integrated process involving the production of hydrogen and an oxide of carbon and the subsequent interaction of the hydrogen and oxide of carbon to produce organic compounds as products of the process.

It has been known for some time that a gaseous mixture comprising hydrogen and carbon monoxide in relatively large proportions may be produced by the reaction of steam and/or carbon dioxide with methane and by the partial combustion of methane. The partial combustion of methane with oxygen as Well as the reaction of methane with carbon dioxide to produce hydrogen and carbon monoxide produces these components in a relatively loW ratio with respect to each other, usually in a mol ratio less than about 2:1 at a temperature between about 1800 and about 2500 F. The production of hydrogen and carbon monoxide by the reaction between methane and steam produces these components in a mol ratio above about 3:1 at a temperature between about 1250 and about 240()o F. Either of the above reactions may be effected with or without a catalyst. The synthesis of organic compounds from such a gaseous mixture comprising hydrogen and carbon monoxide has been effected in the presence of a catalyst, such as a metal or a metal oxide of group VIII of the periodic table. Generally, the mol ratio of hydrogen to carbon monoxide in the feed gas for the synthesis of organic compounds in the presence of such a catalyst is between 1:1 and about 4:1, preferably a ratio of about 2:1.

Each of the above methods for producing hydrogen and carbon monoxide in relatively large proportions have certain inherent disadvantages.

In the partial combustion of methane with oxygen, excess oxygen, which goes to Water, is required to prevent or minimize carbon formation. High temperatures are also required and temperature control is extremely difficult as accurate observation of the exact temperature is substantially impossible.

In the reforming of methane with steam, heat must be supplied to the endothermic reaction. This is accomplished by `means of externally supplied heat, such as by a conventional reforming furnace in which a suitable fuel is burned. The use of a furnace in the reforming operation has its obvious disadvantages. One of these disadvantages is the fact that relatively low presn eures must be used in the reforming furnace because of limitation in the strength of construction materials at an economic temperature, such economic temperature being that temperature at which equilibrium is favorable to a high yield of hydrogen and carbon monoxide. Moreover, the indirect application of heat to the reforming reaction reduces the efficiency of the reforming operation.

It is an object of this invention to overcome such inherent difficulties in the reforming operation and to provide a method for producing a gas comprising hydrogen and carbon monoxide in a mol ratio of about 2:1.

Another object of this invention is to provide a more economic process for the production of a synthesis feed gas having relatively large proportions of hydrogen and an oxide of carbon.

Still another object of this invention is to provide a method and apparatus for producing a synthesis feed gas at relatively high pressures by the reforming of methane.

It is another object of this invention to provide an integrated process for the conversion of a normally gaseous hydrocarbon into hydrogen and an oxide of carbon and the subsequent conversion of the oxide of carbon and hydrogen to hydrocarbons having more than one carbon atom per molecule and oxygenated organic compounds.

Various other objects and advantages of the scription and disclosure.

It is believed that this invention may be best understood and described by reference to the accompanying drawing which shows a diagrammatic arrangement of apparatus in elevation :and partly in cross-section for the manufacture of a gas rich in hydrogen and carbon monoxide and its subsequent use for the synthesis of organic compounds. Although the invention, as described to the drawing, relates to the synthesis of organic compounds, such application of the hydrogen-rich gas should not be considered unnecessarily limiting' in the invention.

ln accordance with the illustration in the drawing, methane or a methane-containing gas from any .suitable source, such as natural gas, after :removal of hydrogen sulfide and other detrimental sulfur compounds therefrom by conventional methods, is passed under pressure through conduits 7, 8 and into a cylindrical elongated reaction chamber E positioned substantially vertically. Although methane is referred to specifically as the feed, the use of other gaseous hydrocarbone, such as ethane and propane, is within the scope of this invention. Oxygen of suitable purity, preferably of about 85 to about 95 per cent purity, is passed to reactor Si through conduits i l and l2, Reactor contains a mass of finelydivided contact material such as a nickel or nichel oxide catalyst, erw-a suitable heat carrying fractory material such'as Alundum. The oxygen and methane gas streams intimately mix and pass upwardly in divided contact material at a linear gas velocity suincient to suspend material in a pseudo-liquid condition. The catalyst mass may be said to be'suspended in the gas stream but not entrained therein inthe sense that there is movement of the catalyst mass as such'in the Ydirection of iiow ofthe gas stream.v

In 'this pseudo-liquid condition it is preferred to maintain the upward velocity oi the 'strc' n sufficiently high to maintain the iuidized catalyst mass in a highly turbulentfcondition in which the particlesv circulate at a high .rate `within the pseudo-liquid mass.

With the contact material ina pseudo-liquid condition in reactor 6, the Asize of the reactor is substantially longer than-that required by the contact or catalyst mass in the fluidized condition. In this manner of operation all but a minor proportion of the catalyst mass is contained in the dense uidized pseudo-liquid which may be designated as the dense phase of the catalyst. This dense phase of catalyst or heat carrying material occupies the lower part ofthe reactor While thatpart of the reactor above the dense phase is occupied by a mixture of gases and powdered catalyst in which the cata-- lyst concentration is much lower, and of a difierent order of magnitude thanthe concentration of the catalyst in the dense phase. This diffuse phase may be said to be a disengaging or settling rone in which solids lifted above the dense phase by the gas stream are disengaged Vthereirorn and returned to the dense phase Vto the extent that such solids are present in the diffuse phase in excess of the carrying capacity of the gas stream Yat the linear velocity thereof.

In the dense phase the-concentrationof Vcatalyst 'in the gas stream varies from a maximum' near the gas inlet of reactor 6 to a minimum in the upper part of this dense phase. Likewise, the vconcentration of the catalyst in the diuse phase varies from a maximum near the upper surface of the dense phase to a minimum in the upper part of reactor t. Y

Between the dense phase of high .average concentration and the diffuse phase of low average kconcentration, there is a relatively narrow Zone in which the concentration ofv solids in the gas stream changes in a short `space from the highY concentration of the Ydense phase to the low concentration of the diffuse phase. This Zone has the appearance of an interface between two visually distinct phases .and is' designated by numeral I4;-

V This dense phase or pseudo-liquid method of operationVv ordinarily involves employment of solid powders and linear gas velocities such that a relatively small proportion of the uidized material is carried away by entrainment and it isnecessary, therefore, to provide meansin reactor t, suchas a cyclone separator it, for separating entrained material and returning it to the dense phase, and/or to providemeans externally of reactor t; such as a Cottrell precipitatoror a liquid scrubber 36, to separate entrainedcontact material from the gaseous eiuent and rethe iinely-divided Contact turn it to reactor 6, or otherwise to recover solid material from the gaseous effluent.

The contact material is employed in a nne state of subdivision. Preferably, the powdered contact material initially contains no more than a minor proportion by weight of material whose particle size is greater than-250 microns. The greater proportion of the catalyst mass comprises material whose particle size is smaller than microns, including atleast 25 weight per cent of material in particle size smaller than 40 microns. The specic 'neness of the contact material required for any operation is determined by such factors as'operating pressure and specific gravity vof the solids. Y

The linear velocity of the gas stream passing upwardthroughfthedense phase is in the range between about 0.1 to about 6 feet per second. The density or concentration of the contact material in the dense phase'will vary and depend upon'such factors as densityof the particles of contactinaterial which in turn depends upon the support used to carry the catalytically activey material, the linear gasl velocity, etc. Generally, the density or concentration of the contactmaterial inthe dense phase is between about 20 andabout `pounds per cubic foot of gas.

In the lower portion of reactor 6 oxygen and methane are combusted to produce hydrogen and carbon monoxide and some carbon dioxide and water. It is preferred to eifect this combustion at a temperature between'about 1200 and about 1800 F.V depending on'the operating pressure. The oxygen and methane are generally preheated to a temperature of about 800 F; and 1000o F., respectively; The introduction ofbothoxygen and methane at a plurality of points longitudinally along reactor 1B vaids in v.minimizing local overheating and assures adequate mixing and distribution of the reactants.' As the `gas stream passes upward tothe lupper portion ofthe dense phase in reactor 5,additional methane Vis. in.- troduced therein through conduit 'i Vand steam is introduced therein through conduit i3.' In the upper portion ofthe dense phase of reactor 6, preferably the upper-one third, steam and methane are endothermically reacted to produce hydrogen and carbon monoxide. YDue to the highrate of internal circulation of the Vcontact material in the i dense phase of reactor 6, the temperature gradient betweenthe upper portion and the lower portionyof the dense phase will be minimum. A pressure betweenr atmospheric and about 300 pounds per square inch gage, preferably below 200 pounds to minimize the amount of methane in the product gas, is maintained on reactor 6.' The upper pressure limit depends upon the product composition desired 'and'on the mechanical limitations of reactor 6 which may .beinternally insulated to assuremaximum the combustion temperaturedepending on-:the rate Vof circulation of the catalyst particles.- In.;

this manner of operation .temperatures may be..-

used which are as much as 500 or `1000" F. lower than those temperatures used in conventional methane combustion processes (combustion alone) for producing hydrogen and carbon monoxide. 'I'he use of lower temperatures results in greatly increased eiiciency because substantially 100 per cent eicient heat transfer is obtained between the exothermic combustion reaction and the endothermic reforming reaction. However, higher temperatures up to the maximum dictated by the mechanical strength of the reactor may be used Without departing from the scope of this invention. The present system is particularly adaptable to the use of a catalyst which increases the capacity of the equipment as the result of higher space velocities.

The quantity of methane introduced into reactor 6 is determined by the carbon requirement (carbon monoxide) ofthe gas product. The relative quantities of oxygen. and steam and/or carbon dioxide introduced into reactor 6 are determined by a heat balance between the methane-oxygen reaction and the methanesteam and/or carbon dioxide reaction at a given temperature level. Generally, the mol ratio of oxygen to total methane introduced into reactor is between about 0.48 and about 0.55. Carbon dioxide may be employed to replace a portion of the steam in the steam-methane reaction, such as by recycling gases from recovery unit 42 to be discussed more fully hereinafter.

As a means of controlling the temperature in reactor t when excess heat is liberated by methane combustion, contact material is withdrawn therefrom by means of standpipe 2l and introduced into conduit 22 stream of steam orrecycle gas and passed through a conventional catalyst cooler 23. The catalyst may be cooled in cooler 23 by either indirect or direct contact with a cooling medium. For eX- ample, the catalyst may be indirectly heat exchanged with Water or steam or the catalyst may be directly contacted with a huid, such a steam, which is later separated from the cooled catalyst. In cooler 23 the gas stream containing suspended Contact material is cooled to a temperature substantially lower than the temperature existing in reactor 6, preferably a temperature at least 300 F. lower than the temperature of reactor 6. The cooled stream of gases and entrained contact material is then passed from cooler '23 through conduit 2d and thence either to separator 25 or directly through conduit 2S to the dense phase or through conduits 2a and 3c to the dilute phase of reactor Separator 2li may be any type of conventional separator for separating gases and finely-divided contact material, such as a cyclone separator of a settling chamber. Gases from the top of separator 26 may be passed directly to reactor t through conduit 32 or may be passed to separate equipment, such as a condenser, when steam is used. Separated contact material is returned to the dilute phase oi reactor 6 through standpipe 2e or part may be recycled through standpipe 2 for temperature control of the hot contact material in standpipe 2i. If desired, separated contact material in standpipe 29 may be injected into the dense phase of reactor 5 by means of standpipe 3 l.

In order to decrease the cost of internally lining standpipe 2l and the use of expensive high temperature valves, means must be provided for lowering the temperature of the catalyst immeiately upon removal from the dense phase of reactor 6. This is accomplished according to a modication of this invention by injecting cooled where it is entrained by a contact material at a temperature substantially lower than the contact material withdrawn from reactor t directly into standpipe 2l at or adjacent the outlet from reactor 6. By continuously recycling a portion of the contact material from reactor s through cooler 23, adequate and full control of the temperature in standpipe 2i and reactor 5 is eected. Suitable aeration gas, such as steam, is introduced into the various standpipes to provide free flow of the solids therein.

A gaseous elucnt comprising hydrogen, carbon monoxide, unreacted steam, methane and carbon dioxide, and containing a small proportion of entrained contact material is passed from reactor li through conduit l1 to a waste heat boiler 33. In waste heat boiler 33 the reaction effluent is cooled to a temperature below about 600c7 generating steam for subsequent use as power and as heat. From waste heat boiler 33 the reaction eiiluent is then passed to solids separator as previously mentioned. Separator 3s may comprise a Cottrell precipitator or liquid scrubbing column for removal of entrained contact material. If a liquid scrubbing column is used for removal of entrained solids, the reaction eiiluent is cooled still further, usually to a temperature below about 200 F'. depending on the pressure. When a Cottrell precipitator is employed, recovered contact material from separator 35 is passed through conduit or standpipe 3l to conduit 22 which returns it to reactor Ei.

At 'this point the reaction eiiluent has approximately the composition shown in the table below when natural gas is the source of methane and when normally gaseous components of synthesis reactor di) are recycled to conduit l'. It will be understood that the composition of the efiluent will depend upon the operating conditions, the composition of the contact material, space velocity, etc.

Table Mol Percent N2 1.0 H2 65.() CO 25.5 CO2 4.5 Clic 4.5

icon

From separator 3S the reaction effluent comprising hydrogen and carbon monoxide in a mol ratio of about 2:1 is passed to a conventional synthesis reactor 45. Synthesis reactor di? comprises any of several types of conventional reaction chambers, such as a xed bed or a fluid-bed reaction chamber, and necessary auxiliary eduip- .ment known to those skilled in the art. Synthesis unit @il may comprise a plurality of reactors in series or in parallel. The synthesis gas feed from conduit 39 is passed through synt esis unit da in contact with a suitable catalyst, such as iron or other metal or metal oxide oi group VIII of the periodic table, under conditions of reaction known to those skilled in the art such that hydrocarbons having more than one carbon atom per molecule and oxygenated organic cornpounds are produced as products oi the process. The temperature of reaction in synthesis unit is generally between about 300 and about S" F. and a pressure is maintained between about atmospheric and about 500 pounds per square inch gage. When employing iron or an iron oxide catalyst, a temperature between about 450 and about 650 F. is appropriate. When employing 1 Contact material may be from the upper portion of the dense phase and a cobalt catalyst` a temperature belowV about 45.0.

F. is employed Sufiicient'contactA time ci .reac` tants and reactionproducts` with the catalyst/ma-4 terial'is afforded in synthesis unit 4c `to produce condensing the synthesis. eiuent and suitable 7' fractionation` and/or extraction equipment for separation andrecovery of the products ci the process. The synthesis reaction eiiiuent is usually cooled toa temperature below about 300 F., preferably below 100 F., in recovery unit d2. The normally gaseous oruncondensed components ci the synthesis reaction effluent are removed from recovery .unit 42 through conduit d6 and may be recycled in whole or in part to synthesis. unit @it through conduit 51, or may be passed in whole or f' in part through conduit 42 'to conduit 2?; orV

through conduit 49 to conduit 1I. Water containing dissolved oxygenated organic compounds is removed from recovery unit d2 through conduit These oxygenated organic compounds may be recovered from the Vwater by conventional methods known to those skilled in the art. i-Iy drocarbons are removed from recovery unit i2 through' conduit i3 for further treatment ror for use as motor fueLesolvents, and chemical reactants. To prevent the build-up of nitrogen in the system a portion of the gases in conduit it mayV be vented therefrom.

The gases in. conduit 48 contain a large proportion of unreacted methane'and carbon dioxide which can be recycled to supplement the feed to reactor `6, such as through conduit i. These recycle gases Vmay also be introduced with the steam in conduit i3, if desired.

passed by externalmeans, such as a standpipe or a Fuller-Kinyon Pump, to the lower portion of the ldense phase in order to aid circulation of the contact material between the zones o exothermis and endothermicreaction without 'departing from the scope of this` invention.

Fresh or regenerated catalyst is introduced into the system through conduit 5| or with the reactants in conduits 1, Il and I3.

Operations according tothe preferred reaction conditions of the Apresent invention produces a gaseous eiiluent from reactor 6 containing hydroand carbon about 1.8:1 and about. 3:.1Yand substantially free from methane witha saving of about 20 per cent oxygen as compared with `conventional partial combustion processes; YThe invention also provides a method for. positive control o the hydro. gen to carbon monoxide ratio in the product gas which makes the process particularly adaptable to the synthesis of organic compounds.

Various other modiiications and alterations or" the apparatus and now may be practiced by .those skilled in the art without departing from the positively withdrawn L monoxide in a mol ratio betweenV scope of thisv invention.` Certain coolers, corrdensers; pumps .and .valves .have .been omitted from' the drawing. asa matter of convenience and clarity and their location "and :use Will .become obvious to vthose skilled in the art.

I claim:

l. A process .for the: production or a gaseous. mixture comprising hydrogen and carbon .monoxa ide in relatively largetproportions .which com'u prises passing reactants and products'oi reaction upward througha mass of. iinelydivided contact material in a reaction zone ata velocity 'sufficient to suspend said mass in a pseudo-liquid4 condition whereby a dense phase of contact material is formed, introducing :oxygen and methane into the lower portion of said dense phase of `contact material .and reacting same to produce-hydrogen and carbon monoxide, introducing methane and steam intothe upper portion of said dense phase and reacting same to produce hydrogenand carbon monoxide, removing an eiiiuent fromsaid Y reaction zone comprisinghydrogen and carbon 'f monoxide as the product of the process, withdrawing a portion of hot contact material Vfrom the dense phase of said reaction zone, cooling saidhot contact materialV withdrawn from said reaction zone to a temperature below the temperature oi said dense phase, returning a portionof the cooled contactmaterialto said reaction zone as a means or controllingithe temperatureof the dense phase `of contact material therein, andadmixing another portion of said cooled contact material withv said withdrawnhcontact material adjacent the point of Withdrawal.

2. A process `for, eiecting an exothermicchem ical reaction Whichcomprises passing reactants and products .of reaction upward through almass of nely divided contact material at an elevated temperature in a reaction Zone at a velocity sui1- cient to.suspend said'mass in a pseudo-liquid condition whereby a dense phase of contact Ymaterial is formed, removingan efliuent from said reaction Zone comprising products of the reaction, withdrawing a portion of hot contact material from the dense phase ofsaid reaction zone, cooling said hot contact material withdrawn fromY said reaction Zonev to a temperature below-the temperature of said dense phase, returning a portion' of Athe cooled contact material to said 'reaction zone' as a means of. controllinggthe tem-V perature of the dense phase or contact material therein and admixing another portion or said cooled contact material with said Withdrawn contact material adjacent the point of withdrawal.

References Cited in the le of Vthis patent UNITED STATES PATENTS Y YOTHER REFERENCES Natta et al.: La Chimica e lIndustria, vol. 19, pages 177-182 (1937). 

1. A PROCESS FOR THE PRODUCTION OF A GASEOUS MIXTURE COMPRISING HYDROGEN AND CARBON MONOXIDE IN RELATIVELY LARGE PROPORTION WHICH COMPRISES PASSING REACTANTS AND PRODUCTS OF REACTION UPWARD THROUGH A MASS OF FINELY-DIVIDED CONTACT MATERIAL IN A REACTION ZONE AT A VELOCITY SUFFICIENT TO SUSPEND SAID MASS IN A PSEUDO-LIQUID CONDITION WHEREBY A DENSE PHASE OF CONTACT MATERIAL IS FORMED, INTRODUCING OXYGEN AND METHANE INTO THE LOWER PORTION OF SAID DENSE PHASE OF CONTACT MATERIAL AND REACTING SAME TO PRODUCE HYDROGEN AND CARBON MONOXIDE, INTRODUCING METHANE AND STEAM INTO THE UPPER PORTION OF SAID DENSE PHASE AND REACTING SAME TO PRODUCE HYDROGEN AND CARBON MONOXIDE, REMOVING AN EFFLUENT FROM SAID REACTION ZONE COMPRISING HYDROGEN AND CARBON MONOXIDES AS THE PRODUCT OF THE PROCESS, WITHDRAWING A PORTION OF HOT CONTACT MATERIAL FROM THE DENSE PHASE OF SAID REACTION ZONE, COOLING SAID HOT CONTACT MATERIAL WITHDRAWN FROM SAID REACTION ZONE TO A TEMPERATURE BELOW THE TEMPERATURE OF SAID DENSE PHASE, RETURNING A PORTION OF THE COOLED CONTACT MATERIAL TO SAID REACTION ZONE AS A MEANS FOR CONTROLLING THE TEMPERATURE OF THE DENSE PHASE OF CONTACT MATERIAL THEREIN, AND ADMIXING ANOTHER PORTION OF SAID COOLED CONTACT MATERIAL WITH SAID WITHDRAWN CONTACT MATERIAL ADJACENT THE POINT OF WITHDRAWAL. 